The present invention relates to a shut-off and control valve for use in regulating the discharge of molten metal from a metallurgical vessel, particularly into a continuous casting plant for continuous casting of a sheet or strip or thin slab having a relatively wide width, and wherein such valve regulates the discharge of the molten metal through an outlet of the metallurgical vessel that is elongated. The present invention also relates to a refractory stator and to a refractory rotor employable in such shut-off and control valve.
It is know, for example, as disclosed in DE-OS 35 08 218, to regulate the flow of an elongated discharge of molten metal from a metallurgical vessel by means of chambers defined by walls, particularly for a continuous casting operation. In such arrangement, the flow of the molten metal, to be adapted to particular casting requirements, is controlled by adjusting the viscosity of the molten metal by means of the temperature of the molten metal by cooling and/or heating and is dependent on flow velocity. This arrangement particularly is advantageous for continuous casting when the flow of molten metal is to be influenced by narrow pipes or gaps, either feed or sealing segments. An induction coil driven by high frequency electric current is provided as the heating element. Such a device is relatively expensive both to construct and to operate and is not suitable to achieve rapid opening and closing of the discharge outlet.
In a continuous casting system, molten metal is guided continuously under the metallostatic pressure of the molten metal within the metallurgical vessel into an inlet or funnel of a crystallizer or plate mold of a continuous casting plant. Accordingly, the feed of the molten metal into the mold cannot be controlled independently of the metallostatic pressure within the metallurgical vessel.
In a continuous strip casting system disclosed in EP-OS 0 233 481, the bottom of the metallurgical vessel is provided with a slotted outlet, beneath which are mounted two pairs of slide valve plates that can be adjusted relative to one another and that can be moved through a defined slot between the closed and open positions to control the discharge flow of molten metal. This system is relatively expensive to build and, since the shut-off device must be mounted below the vessel, the accuracy of such device is limited at relatively large strip dimensions due to the varying thermal stresses on the slide valve plates caused by temperature gradients.